history()

Page four of the introduction summarizes user expectations, with a reference to William J. Cody's Fortran MACHAR routine. In its time, Software Manual for the Elementary Functions was an excellent reference for implementing, and especially testing, elementary functions.

def history():
    """Present a bit of historical context and set user expectations."""
    hist = [
        "The program attempts to discriminate among",
        "   FLAWs, like lack of a sticky bit,",
        "   Serious DEFECTs, like lack of a guard digit, and",
        "   FAILUREs, like 2+2 == 5 .",
        "Failures may confound subsequent diagnoses.",
        "\nThe diagnostic capabilities of this program go beyond an earlier",
        "program called `MACHAR', which can be found at the end of the",
        "book  `Software Manual for the Elementary Functions' (1980) by",
        "W. J. Cody and W. Waite. Although both programs try to discover",
        "the radix, precision, and range (over/underflow thresholds)",
        "of the arithmetic, this program tries to cope with a wider variety",
        "of pathologies, and to say how well the arithmetic is implemented.",
        "\nThe program is based upon a conventional radix representation for",
        "floating-point numbers, but also allows logarithmic encoding",
        "(radix B=1) as used by certain early WANG machines.\n"
    ]
    print_msgs(hist)
    return